Chemical Mystery #8: Go Blue!

Tom Kuntzleman | Fri, 11/04/2016 - 13:36

In the state of Michigan where I live, the University of Michigan (UM) and Michigan State University (MSU) are rivals. Green is the definitive color of MSU, whereas blue and gold are the school colors of UM. I went to school at UM, so naturally I am partial to blue and gold. Watch the video below to see if you can figure out how I change green into blue and gold in this simple chemistry experiment:

See the Solution to Chemical Mystery #8!

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Comments 6

my solution to mystery #8

Solution of isopropyl alcohol in water and blue and yellow food dye. Add potassium carbonate solid. Just re-created this for my 7th period class. Magic!

reply - mystery #8

Yes, it worked fine (70% v/v isopropyl from the grocery store)- but it does take a lot of potassium carbonate. I have added blue dye to the alcohol, yellow to water, and mixed all before adding the solid, just like you did. I have done it also with ethanol in the past but the some of the yellow dye partitions into ethanol, making it blue-green rather than blue solution.

I'll have to try that...

Grazyna...Did the recipe you cite above actually work? I've never tried it that way! I actually pulled off the trick a little differently.

I'm going to have to try your method to see what kinds of colors I get. In any event, well done!

explanation wanted

Hi Tom, that's fantastic.

I was thinkering to some cobalt(III) thiocyanate generated from a Co(II) green salt that was extracted in an ethereal solvent.

But the "big" problem was: how can you yield two liquid phases if you start from just one?

Now I see that you have used just two food dye, but the main problem remain: how can happen that you obtain two liquids from one?

I can try one hypothesis: the initial rubbing alcohol is a water mixture, mybe 50%. isopropanol has unlimited solubility in water but, when the ionic strength of the solution increases as a consequence of the huge amount of salt you have dissolved, the single phase becomes unstable and separates into two, salt water and isopropanol saturated with water, where the two dye have differential solubility. It is that?